Search results for "Zero-point energy"
showing 10 items of 20 documents
Zero‐Energy Rotating Accretion Flows near a Black Hole
1996
We characterize the nature of thin, axisymmetric, inviscid, accretion flows of cold adiabatic gas with zero specific energy in the vicinity of a black hole by the specific angular momentum. Using two-dimensional hydrodynamic simulations in cylindrical geometry, we present various regimes in which the accretion flows behave distinctly differently. When the flow has a small angular momentum $(\lambda\lsim\lambda_b)$, most of the material is accreted into the black hole forming a quasi-spherical flow or a simple disk-like structure around it. When the flow has a large angular momentum (typically, larger than the marginally bound value, $\lambda\gsim\lambda_{mb}$), almost no accretion into the …
Quantum Monte Carlo methods
2005
Introduction In most of the discussion presented so far in this book, the quantum character of atoms and electrons has been ignored. The Ising spin models have been an exception, but since the Ising Hamiltonian is diagonal (in the absence of a transverse magnetic field), all energy eigenvalues are known and the Monte Carlo sampling can be carried out just as in the case of classical statistical mechanics. Furthermore, the physical properties are in accord with the third law of thermodynamics for Ising-type Hamiltonians (e.g. entropy S and specific heat vanish for temperature T → 0, etc.) in contrast to the other truly classical models dealt with in previous chapters (e.g. classical Heisenbe…
van der Waals Interaction Energy Between Two Atoms Moving With Uniform Acceleration
2013
We consider the interatomic van der Waals interaction energy between two neutral ground-state atoms moving in the vacuum space with the same uniform acceleration. We assume the acceleration orthogonal to their separation, so that their mutual distance remains constant. Using a model for the van der Waals dispersion interaction based on the interaction between the instantaneous atomic dipole moments, which are induced and correlated by the zero-point field fluctuations, we evaluate the interaction energy between the two accelerating atoms in terms of quantities expressed in the laboratory reference frame. We find that the dependence of the van der Waals interaction between the atoms from the…
The momentum and the angular momentum of the Universe revisited. Some preliminary results
2007
We consider the question of properly defining energy and momenta for non asymptotic Minkowskian spaces in general relativity. Only those of these spaces which have zero energy, zero linear 3-momentum, and zero intrinsic angular momentum would be candidates to creatable universes, that is, to universes which could have arisen from a vacuum quantum fluctuation. Given a universe, we completely characterize the family of coordinate systems in which it would make sense saying that this universe can be a creatable universe.
The zero-point energy for rotation
1978
The Gaussian overlap approach (GOA) becomes inappropriate for describing the rotation of weakly deformed systems. A modification is proposed which allows to maintain the GOA for small deformations. The zero-point energy subtraction, derived from it, provides a simple and reliable approximation for angular momentum projection. It becomes obvious, however, that the projection complicates the equations which determine the motion along the deformation path. These effects are studied in some simple models and the results are condensed into a simple interpolation formula for the total zero-point energy.
Systematics of parton-medium interaction from RHIC to LHC
2011
Despite a wealth of experimental data for high-P_T processes in heavy-ion collisions, discriminating between different models of hard parton-medium interactions has been difficult. A key reason is that the pQCD parton spectrum at RHIC is falling so steeply that distinguishing even a moderate shift in parton energy from complete parton absorption is essentially impossible. In essence, energy loss models are effectively only probed in the vicinity of zero energy loss and, as a result, at RHIC energies only the pathlength dependence of energy loss offers some discriminating power. At LHC however, this is no longer the case: Due to the much flatter shape of the parton p_T spectra originating fr…
Effect of zero-point motion on the superconducting transition temperature of PdH(D)
1984
Using self-consistent density functional formalism we show that the electronic structure of PdH(D) is influenced by the zero-point vibration of hydrogen and deuterium. This quantum effect makes a small but significant contribution to the superconducting transition temperature ${T}_{c}$ of PdH(D). The reverse isotope effect on ${T}_{c}$ is found to be dominated by the changes in the force constants between PdH and PdD.
Convergent transformations into a normal form in analytic Hamiltonian systems with two degrees of freedom on the zero energy surface near degenerate …
2004
We study an analytic Hamiltonian system with two degrees of freedom, having the origin as an elliptic singularity. We assume that the full Birkhoff normal form exists and is divisible by its quadratic part, being indefinite. We show that under the Bruno condition and under the restriction to the zero energy surface, a real analytic transformation into a normal form exists. Such a normal form coincides with the restriction of the Birkhoff normal form to the zero energy surface up to an order as large as we want.
Quantum memories with zero-energy Majorana modes and experimental constraints
2016
In this work we address the problem of realizing a reliable quantum memory based on zero-energy Majorana modes in the presence of experimental constraints on the operations aimed at recovering the information. In particular, we characterize the best recovery operation acting only on the zero-energy Majorana modes and the memory fidelity that can be therewith achieved. In order to understand the effect of such restriction, we discuss two examples of noise models acting on the topological system and compare the amount of information that can be recovered by accessing either the whole system, or the zero-modes only, with particular attention to the scaling with the size of the system and the e…
On the convergence of zero-point vibrational corrections to nuclear shieldings and shielding anisotropies towards the complete basis set limit in wat…
2016
The method and basis set dependence of zero-point vibrational corrections (ZPVCs) to nuclear magnetic resonance shielding constants and anisotropies has been investigated using water as a test system. A systematic comparison has been made using the Hartree–Fock, second-order Møller–Plesset perturbation theory (MP2), coupled cluster singles and doubles (CCSD), coupled cluster singles and doubles with perturbative triples corrections (CCSD(T)) and Kohn–Sham density functional theory with the B3LYP exchange-correlation functional methods in combination with the second-order vibrational perturbation theory (VPT2) approach for the vibrational corrections. As basis sets, the correlation consisten…